Ion exchange membranes based upon crosslinked sulfonated polyethersulfone for electrochemical applications

• Synthesis of new non-fluorinated crosslinked ion exchange membranes.
• Membranes with improved durability and high proton conductivity.
• Performances of crosslinked membranes in PEMFC are comparable with those of Nafion.

Synthesis and characterization of new ion exchange membranes made from chlorosulfonated polyethersulfone (SO2Cl-PES) crosslinked by polyaminated crosslinking reagents have been performed. Two examples are described: one crosslinked by hexane diamine, the other by amino-polyethersulfone (NH2-PES). Sulfonated polyether sulfone (S-PES) and NH2-PES have similar chemical structures that allow compatibility. Surprisingly enough, better results were obtained using amino-polyethersulfone. The best results have been obtained using SO2Cl-PES with 1.3 SO2Cl group per monomer unit crosslinked by 0.2 equivalent of NH2-PES. The membranes, less brittle than pristine SPES and insoluble in solvents such as DMAc, were characterized by TGA, DMA, DSC, ionic conductivity, transport numbers, and water swelling. The results showed that these membranes presented very promising performances for use in Proton Exchange Membrane Fuel Cells.